integral of lnx. Natural log of x is u-- we set that equal to natural log of x-- times du. integral of lnx

 
 Natural log of x is u-- we set that equal to natural log of x-- times duintegral of lnx The value of the integral of x can be computed using the power rule, (int x^{n}dx = frac{x^{n+1}}{n+1} + C), with n = 1

Anyway, to integrate ln (x), we use Integration by Parts (have you covered Integration by Parts yet?), i. Free integral calculator - solve indefinite, definite and multiple integrals with all the steps. onumber ] The last integral is now the same as the original. en. Free integral calculator - solve indefinite, definite and multiple integrals with all the steps. Plugging this in the previous result: #int (lnx)^2dx = x(lnx)^2-2xlnx+2x+C= x(ln^2x-2lnx+2)+C#🏼 - Integral of sin(ln(x)) - How to integrate it step by step using integration by parts!🔍 𝐀𝐫𝐞 𝐲𝐨𝐮 𝐥𝐨𝐨𝐤𝐢𝐧𝐠 𝐟𝐨𝐫. Then: I = ∫(lnx)2( 1 x dx) = ∫u2du = 1 3u3 = 1 3 (lnx)3 +C. Type in any integral to get the solution, steps and graph. Since the derivative of ln x is 1/x, the anti-derivative of 1/x is ln x. ∴ I = − lnx x +∫ 1 x2 dx. Then, ∫ log(log(x))dx = x log(log(x)) − ∫ 1 log(x) dx = x log(log(x)) − li(x) + C ∫ log ( log ( x)) d x = x log ( log ( x)) − ∫ 1 log ( x) d x = x log ( log ( x)) − li ( x) + C. Derivatives Derivative Applications Limits Integrals Integral Applications Integral Approximation Series ODE Multivariable Calculus Laplace Transform Taylor/Maclaurin Series Fourier Series Fourier Transform. It follows that, in your notation, and the result follows. The derivative of the logarithm ( ln x ) is ( frac{1}{x} ), but what is the antiderivative?This turns out to be a little trickier, and has to be done using a clever integration by parts. Type in any integral to get the solution, steps and graph. Organic Chemistry Tutor - Playlists:. To integrate ln x by parts, let u= ln x, dv= dx. Related Symbolab blog posts. Tap for more steps. Fact 1: F is continuous and strictly increasing. ∫ x ln x dx =Ei(2 ln x) + C. If you would, and to be complete, cite your references for the known integrals. integral-calculator. . . Join this channel and unlock members-only perks. Choose "Evaluate the Integral" from the topic selector and click to. using integration by parts. Free antiderivative calculator - solve integrals with all the steps. . Type in any integral to get the solution, steps and graph. Natural log of x is u-- we set that equal to natural log of x-. Firstly log (ln x) has to be converted to the natural logarithm by the change of base formula as all formulas in calculus only work with logs with the base e and not 10. Type in any integral to. where li(x) li ( x) is given by. 44, 1. To find an antiderivative of lnx, we must find ∫lnxdx. 7182. It helps. . Essentially, it undoes the product rule of differentiation. A monster antiderivative $intln(Acosh(alpha x)+Bsinh(alpha x)+C)dx$ 1. It is denoted by ∫ (sin (ln x))dx. . Practice Makes Perfect. Postagens de blog relacionadas ao Symbolab. We would like to show you a description here but the site won’t allow us. integral ln(x)dx. integral \int 1/ln x. Let us take, u = ln (x) and . 20: ∫ 0 2 x ln x d x = lim t → 0 + ∫ t 2 x ln x d x Rewrite as a limit. The integral of ln x with limits from 0 to 1 is given by, The function ln x is a logarithm to the base e, where e is the Euler’s number equals to 2. int1/ (xlnx)dx=int (1/lnx)1/xdx=int1/udu This is a common integral: int1/udu. calculus-calculator int lnxdx. The function ln x is also known as the natural log of x. en. Hence, the required integral is ∫ ln x = x ln x-x + C,where C is a constant. Now, one thing that must be noted is that, the correct choice of first function and second. Calculus 1 Final Exam Review:. I would start with a u-substitution and separate the integral. 🏼 - Integral of ln(1+x^2) - How to integrate it step by step using integration by parts!🔍 𝐀𝐫𝐞 𝐲𝐨𝐮 𝐥𝐨𝐨𝐤𝐢𝐧𝐠 𝐟𝐨𝐫. Difficult problem in Riemann integrals. en. integral ln(x)dx. . You can use integration by parts to get a reduction formula. 🏼 - Integral of ln(x)/sqrt(x) - How to integrate it step by step using integration by parts!👋 𝐅𝐨𝐥𝐥𝐨𝐰 @𝐢𝐧𝐭𝐞𝐠𝐫𝐚𝐥𝐬. What does to integrate mean? Integration is a way to sum up parts to find the whole. Related Symbolab blog posts. The antiderivative of 1 lnx is called the logarithmic integral function, and is denoted li(x) It is generally not included in an introductory calculus course (or sequence of courses). . The integration of lnx l n x is of the form. In order to use sin(lnx)dx in dv, we'll need to be able to integrate dv. 1. ∫arctanxdx = xarctanx − ∫ x 1 + x2 dx. Examples. If you can use the chain rule and the fact that the derivative of ex is ex and the fact that ln(x) is differentiable, then we have: d dxx = 1. So consider the second function as 1 1. Now, apply the values in the formula and integrate the function, Hence, ∫ ln (x) d x = x ln (x) − ∫ x d d x (ln (x)) d x = x ln (x) − ∫ x × 1 x d x = x ln (x) − ∫ d x = x ln (x) − x + C. You can also get a better visual and understanding of the function and area under the curve using our graphing tool. The Integration by Parts formula gives. Now, handling the second integral, first of all let's factor out the constant and write x2 as x2 + 1 − 1 to split it up : ∫. Differentiate with respect to x. Trigonometric integral. Set up the integral to solve. Step 5. The first rule to know is that integrals and derivatives are opposites! Sometimes we can work out an integral, because we know a matching derivative. Hopefully you can spot that lnx is not easy to integrate (you need to using. We can do integration by parts, however, letting: {u = (lnx)2 =⇒ du = 2lnx x dx dv = 1 xdx =⇒ v = lnx. en. Advanced Math Solutions – Ordinary Differential Equations Calculator, Exact Differential Equations. So consider the second function as 1 1. or we can use another method eg IBP. For instance, the derivative of lnx is 1 x which looks promising since it's the same as the other factor. continued fraction identities containing integrals. Related Symbolab blog posts. If we set our u equal to natural log of x, then our du is 1/x dx. Integral of ln(x^n) - How to integrate it by parts step by step!👋 Follow @integralsforyou on Instagram for a daily integral 😉📸 @integralsforyou = dx x. #int u v' = uv - int u' v# #I = int ln x / x dx# #= int d/dx(ln x) ln x dx# #= ln x ln x - int ln x d/dx(ln x) dx# #= ln^2 x - int ln x/x dx# #implies I = ln^2 x - I + C#Secondly, I have attempted to find the n n th integral of ln(x) ln ( x) and this is what I found. @DavidH thank you. Calculate limits, integrals, derivatives and series step-by-step. If \(x>0\) and \(y=\ln x\), then \(e^y=x. Keep in mind: ln( x−−√) = ln(x) 2. There are other solutions: Both of the solution presented below use Integration by Parts. Integral cosine in the complex plane. The suggestion is made to consider improper integrals, and the conversation then delves into the process of solving the integral using integration by parts. Note that both of these are currently present in the integral. The logarithmic integral (in the "American" convention; Abramowitz and Stegun 1972; Edwards 2001, p. It is used to transform the integral of a. The integral (antiderivative) of lnx is an interesting one, because the process to find it is not what you'd expect. 1 Answer Jim H Apr 6. calculus-calculator \int \frac{1}{lnx}dx. integral ( ln x )^2 d x. Using ln(e) = 1: = ∫ ln(x) + x x dx. Related Symbolab blog posts. I edited my usage of integration, in this step I am lost. Functions. In the previous posts, we have covered three types of ordinary differential equations, (ODE). This is one of the maths problems where you need to learn a little trick and write #lnx# as the product #(1)(lnx)#. The integral of ln x ln x squared is of the form. According to the properties of logarithms, we know that. If we set our u equal to natural log of x, then our du is 1/x dx. In this video, we work through the derivation of the reduction formula for the integral of ln^n(x) or [ln(x)]^n. To evaluate this integral first we use the method of substitution and then we use integration by parts. Type in any integral to get the solution, steps and graph. Calculate limits, integrals, derivatives and series step-by-step. ∫ ln ( x) 2 d x. The integral on the right can be solved by substitution. But how to prove this? Before proving the derivative of ln x to be 1/x, let us prove this roughly by using its graph. Similar questions. Furthermore, the function y = 1 t > 0 for x > 0. Related Symbolab blog posts. It's going to be equal to pi times the indefinite integral of 1/u. int sin (2x)dx. Natural Logarithms (Sect. Using integration by parts. Learn how the integral of ln(x) is solved. Dado que la derivada de ln ( x ) es bien conocida como 1 / x , probablemente sería una buena idea dejar u = ln ( x ). It may seem that we have simply gone in a circle, but now we can actually evaluate. . "Integration by Substitution" (also called "u-Substitution" or "The Reverse Chain Rule") is a method to find an integral, but only when it can be set up in a special way. The Fundamental Theorem of Calculus allows a definite integral to be evaluated using the anti-derivative. Now we can make some substitutions to the original integral. ∫ x ln x dx =Ei(2 ln x) + C. 1 Answer Truong-Son N. This order of priority can help you decide. We have now reached. . Answer link. Type in any integral to get the solution, steps and graphSymbolab is the best integral calculator solving indefinite integrals, definite integrals, improper integrals, double integrals, triple integrals, multiple integrals, antiderivatives, and more. Since the original function involves lnx, we are justified in assuming that x>0 and writing: int x^(-lnx) dx =lnx+C. . However, because when t is 0, the Ei function is undefined at 0, you must make it the sum of two integrals approaching 0. Sabemos que nuestras dos funciones son ln ( x ) y 1. This calculus video tutorial explains how to find the integral of lnx/x^2 using integration by parts. Save to Notebook! Free integral calculator - solve indefinite, definite and multiple integrals with all the steps. int lnx. You may also need to use some trigonometric identities and the relationship θ = sec −1 ( x a ) . Advanced Math Solutions – Integral Calculator, the complete guide. Integrate by parts using the formula, where and . d dxeln ( x) = eln ( x) d dxln(x) = 1. Even though derivatives are fairly straight forward, integrals are. 26), is defined for real as. Step 2. Integrate functions involving logarithmic functions. integral-calculator int lnx dx. In general, it's always good to require some kind of proof or justification for the theorems you learn. Note, there is no x x in that expression except on the limits. But ln(x) is a logarithmic function defined only for x-values greater than zero, while 1/x is a rational function defined for all non-zero x's. Cite. However, the integral you have requested is indefinite, which equals to the. It is relevant in problems of physics and has number theoretic significance. Integration by Substitution. Type in any integral to get the solution, steps and graph. Type in any integral to get the solution, steps and graph. I = ∫xsin(lnx) 1 x dx. The definite integral of from to , denoted , is defined to be the signed area between and the axis, from to . Just like running. Answer link. Entonces, dejaremos dv = 1 dx. Difficult integral involving $arctan x$ Hot Network Questions How is St. integral-calculator int e^{lnx}dx. 1. freak667. ∫ sin log x dx = x sin log x − ∫ cos log x dx. )45451 views around the world You can reuse this answer Creative Commons LicenseI am quite confused about how the integral definition is used to prove $ln(xy)= ln(x)+ ln(y) $ below, especially in how it does not treat the integrand as a strict reciprocal function; and even if it did I am not seeing how the bounds apply. Splitting the fraction ( x x = 1 ): = ∫ ( ln(x) x + 1)dx. I Integrals involving logarithms. It is used to find the area under a curve by slicing it to small. In mathematics, trigonometric integrals are a family of integrals involving trigonometric. Taking the derivative of both sides: d dx u = d dx lnx. Method 2. Find the integration of ln x. Learning math takes practice, lots of practice. Step 2. I = =∫ π 4 0 ln(1 + tan x)dx +∫ π 2 π 4 ln(1 + tan x) dxx→π 2−x 2∫ π 4 0 ln(1 + tan x)dx −∫ π 4 0 ln(tan x)dx = π 4ln 2 + G. Indefinite integration of $ln(1+x^2)arctan x$ 4. e: We often use Integration by Parts, when no other methods can solve the integral. Integral of two modified Bessel functions of order 0 and 1. Derivatives Derivative Applications Limits Integrals Integral Applications Integral Approximation Series ODE Multivariable Calculus Laplace Transform Taylor/Maclaurin Series Fourier Series. I'm pretty sure that cut is the result of using the principal branch of $log(1+z^{2})$. Answer: the integral of ln (x) is xln (x) - x + C. How do you find the integral of #int (lnx / sqrt(x)) dx# from 0 to 1? Calculus Introduction to Integration Definite and indefinite integralsSquare root of a square in an integral. Free integral calculator - solve indefinite, definite and multiple integrals with all the steps. Type in any integral to get the solution, steps and graph. In this video I show you how to integrate ln x. Let: u = x+1 du = dx x = u - 1 => int (u-1)lnudu = int u lnudu - int lnudu With these two integrals in mind, we can do Integration by Parts. How to integrate ln(2x) by using the integration by parts methodThe integration technique involved here is to realize that ln(2x)dx is the same as ln(2x) tim. Step 2: Click the blue arrow to submit. So would it be more accurate to say: the derivative of ln(x) is 1/x such that x is greater than zero?. The first definition I found is that. ∫ + ∞ 0 e − xlog(x)dx = Γ ′ (1) = Γ(1)ψ(1) = − γ follows from differentiation under the integral sign, as shown by Felix. integral ln|x| en. We have: ln(x) = ∫x 1 1 tdt ln ( x) = ∫ 1 x 1 t d t. Tap for more steps. To do so, we use integration by parts. If (x>0) and (y=ln x), then (e^y=x. The derivative of ln x is 1/x. pt. We rewrite the integral as ln (x) times 1dx, then choose f (x) = ln (x) and g' (x) = 1. Important Notes on Antiderivative of ln x. Plugging this in the previous result: #int (lnx)^2dx = x(lnx)^2-2xlnx+2x+C= x(ln^2x-2lnx+2)+C#🏼 - Integral of sin(ln(x)) - How to integrate it step by step using integration by parts!🔍 𝐀𝐫𝐞 𝐲𝐨𝐮 𝐥𝐨𝐨𝐤𝐢𝐧𝐠 𝐟𝐨𝐫. intcos (lnx)/xdx=sin (lnx)+C A substitution solves this. Related Symbolab. Just like. Practice Makes Perfect. Related Symbolab blog posts. integral of arctan(ln(x), 1/ln(x)) area between ln(x) and x-axis from x = 0 to 1; integrate x ln(x) integrate x^lnx ; Riemann surface 1/4 z^2 (2 log(z)-1) Integration by parts: ∫ln (x)dx. ax = elnax = exlnx. 1. The antiderivative is xln (x) - x + C. Cancel the common factor. . Evaluate \displaystyle {\int \ln 2x \, dx} ∫ ln2xdx. The integration-by-parts formula can be written in abstract form as: ∫u dv = uv −∫v du. Save to Notebook! Free integral calculator - solve indefinite, definite and multiple integrals with all the steps. asked Jun 16, 2016 at 11:32. Step 6. ∫ u d v = u v − ∫ v d u. \) Differentiating both sides of this equation results in the equation \(e^y\frac{dy}{dx}=1. Related Symbolab blog posts. In this video I demonstrate how to find the integral or antiderivative of the natural log of x, ln(x), using integration by parts. Answer link. Evaluate the integral of (ln x)^2 dx. integral-calculator. Related Symbolab blog posts. When using integration by parts it must have at least two functions, however here there is only one function: ln x ln x. Both types of integrals are tied together by the fundamental theorem of calculus. . Free integral calculator - solve indefinite, definite and multiple integrals with all the steps. Integral(ln(x)) = xln(x) - Integral(x1/x) Awesome. ∫udv. You can also use the change of variable formula setting. integral-calculator. Generally speaking, "using ln(x) " as a rule or technique is unheard of. We then have. Find the integral of (x + 1) ln x dx. Type in any integral to get the solution, steps and graph. Step 5. Si ( x) (blue) and Ci ( x) (green) plotted on the same plot. The integral of Sqrt x lnx is of the form. Advanced Math Solutions – Integral Calculator, the complete guide. Share. What is the step-by-step solution for the following integral: ∫alnxdx. Recall that lnx is the inverse of the function ex. Let tan x = t 2 such that tan 2 x = t 4 and sec 2 x = 1 + t 4. Type in any integral to get the solution, steps and graph. Using the formula. #intudv = uv - intvdu# To accomplish this, we must choose a term for #u#, and another for #dv#. Free integral calculator - solve indefinite, definite and multiple integrals with all the steps. The logarithmic integral defined in this way is implemented in the Wolfram Language as LogIntegral [ x ]. Making necessary. For the first integral, consider the substitution x = ln(1 / u) i. It's going to be equal to pi times the indefinite integral of 1/u. Strategy: Use Integration by Parts. I = ∫ (lnx)2 x dx. $$ ∫ \ln(x)\,dx\,, $$ but integration by parts requires two. Related. en. 1 AnswerIntegral of ln(x)/x^4 - How to integrate it by parts step by step!👋 Follow @integralsforyou on Instagram for a daily integral 😉📸 @integralsforyou this video, we work through how to integrate ln^2(x). 🏼 - Integral of ln(sqrt(x)) - How to integrate it step by step using integration by parts!🔍 𝐀𝐫𝐞 𝐲𝐨𝐮. Advanced Math Solutions – Integral Calculator, common functions. Simplify. Let: u = x+1 du = dx x = u - 1 => int (u-1)lnudu = int u lnudu - int lnudu With these two integrals in mind, we can do Integration by Parts. Defined as the logarithm to base e e or the inverse function of the exponentiation to base e e: ln(x) = y ey = x ln. ln(x) dx set u = ln(x), dv = dx then we find du = (1/x) dx, v = x substitute ln(x) dx = u dv and use integration by parts = uv - v du substitute u=ln(x), v=x, and du=(1/x)dx = ln(x) x - x. Combine and . I would avoid the notation unless I explain at the outset what I mean by it. Related Symbolab blog posts. It is denoted by ∫(ln x)dx. Now, one thing that must be noted is that, the correct choice of first function and second. Thanks. Lets start by breaking down the function. Advanced Math Solutions – Ordinary Differential Equations Calculator, Exact Differential Equations. Step 3. en. For the second integral choose u = sin log x and dv = dx. . But since y = ln(x) y = ln ( x), we have ey =eln(x) = x e y = e ln ( x) = x and so our original. Symbolab is the best integral calculator solving indefinite integrals, definite integrals, improper integrals, double integrals, triple integrals, multiple integrals, antiderivatives, and more. $int_0^1 ln x = x(ln x -1) |_0^1 = 1(ln 1 -1) - 0 (ln 0 -1)$ Is the second part of the calculation indeterminate or 0? What am I doing wrong? Thanks Joachim G. The first and most vital step is to be able to write our integral in this form: This integral is good to go!Advanced Math Solutions – Integral Calculator, the basics. Integration is the basic operation in integral calculus. Integration by parts is wri. Simplify. integral-calculator. We apply the formula of definite integrals (intlimits_a^b f(x) dx) = f(b) - f(a). Though the 'at ease' part is usually the hardest! However, I do believe the greatest trait for any mathematician is luck. It is denoted by ∫ (cos (lnx))dx. Let: #u = ln(x+1)# #du = 1/(x+1)dx# #dv = 1dx# #v = x# #uv - intvdu#. For each of the three functions f , g, and h, compare the results of L1, R1, M1, T1, and S2 to the true value of the corresponding definite integral. However, I will show. This includes integration by substitution, integration by parts, trigonometric substitution and integration by partial fractions. integral int ln(x) en. Calculus Introduction to Integration Integrals of Exponential Functions. Related Symbolab blog posts. en. The logarithm is a basic function from which many other functions are built, so learning to integrate it substantially broadens the kinds of integrals we can tackle. Solve problems from Pre. I = ∫ln x ⋅ 1dx – – – (i) I = ∫ ln x ⋅ 1 d x – – – ( i) Integration of lnx. Created by Sal Khan. In:= ∫xm ln(x)ndx I n := ∫ x m ln ( x) n d x. ln (abslnx)+C We have the integral: int1/ (xlnx)dx Use substitution. However, I often use integration by parts and I wonder what is wrong here, and what should I do to avoid it (here it's plainly wrong, but what if the mistake was more subtle?). Integration by Parts Sqrt x ln x. i. So: limx→∞ ln(x) = ∫∞ 1 1 tdt lim x → ∞ ln ( x) = ∫ 1 ∞ 1 t d t. Step 2: Substitute the variables. Related Symbolab blog posts. calculus-calculator int lnxdx. The indefinite integral cannot be expressed in terms of elementary functions. ln(x) dx set u = ln(x), dv = dx then we find du = (1/x) dx, v = x substitute ln(x) dx = u dv and use integration by parts The formula for the integral of ln x is given by, ∫ln x dx = xlnx - x + C, where C is the constant of integration. We will be using integration by parts in order to take the integral of ln x. Compute answers using Wolfram's breakthrough technology &. This calculus video tutorial explains how to find the integral of lnx/x using the u-substitution integration technique. Repeat as needed to reduce the exponent to zero, and one sees that the limit is zero. I'd like a hint toward how I could evaluate this definite integral. ∫logaxdx = x lna(lnx − 1) + C. The Art of Convergence Tests. Example. Conic Sections Transformation. QUICKLY find the integral of ln x using integration by parts! (this is also known as the antiderivative of ln x)#math #brithemathguy #shorts BECOME A CHANNE. Using logarithm rules, we get: = ∫2lnx dx. In mathematics, the logarithmic integral function or integral logarithm li ( x) is a special function. 1. . integral-calculator. integral \int ln(x) en. In summary, the conversation discusses attempting to solve a definite integral using integration by parts, but encountering an undefinable term. 12. Integral of ln(x)/x - How to integrate it step by step using the substitution method!👋 Follow @integralsforyou on Instagram for a daily integral 😉📸 @integ. Free integral calculator - solve indefinite, definite and multiple integrals with all the steps. Save to Notebook! Free integral calculator - solve indefinite, definite and multiple integrals with all the steps. The function ln x is also known as the natural log of x. (xln (x)) int e^xcos (x)dx int_{0}^{pi}sin(x)dx sum_{n=0}^{infty}frac{3}{2^n} Show More; Description. Cite. In this video I will teach you how to integrate ln(x^2). en. Now that we know how to integrate this, let's apply the properties of logarithms to see how to work with similar problems. 9 to rewrite the result in terms of x . =. Integration by parts is not necessary. This lesson covers the steps to solve, including application and solution, and takes a look at. This is a common integral, where ∫lnx dx = xlnx − x + C. integral int ln (x)dx. I'm assuming that we have ∫lnx2 dx. High School Math Solutions – Partial Fractions Calculator. integral-calculator. Step 6. 5,192 2 2. Type in any integral to get the solution, steps and graph. e. Note: x > 0 is assumed throughout this article, and the constant of integration is omitted for simplicity. The Integral Calculator lets you calculate integrals and antiderivatives of functions online — for free! Our calculator allows you to check your solutions to calculus exercises. So I think setting ln2(x) to be f(x) would be easier, since differentiating it would get us 2lnx x. int lnx /x^3 dx = (-lnx)/(2x^2 ) - 1/(4x^2) + C You should learn the IBP formula: int u(dv)/dxdx=uv - int v (du)/dxdx So essentially we are looking for one function that simplifies when it is differentiated, and one that simplifies when integrated (or at least is integrable). So the integration of lnx is equal to ∫ln (x)= xlnx-x+C and this is derived using the integration by parts formula. By part : intln (sqrt (x))dx du = 1 u = x v = ln (sqrt (x)) dv = 1/ (2x) [xln (sqrt (x))]-1/2intdx [xln (sqrt (x))-1/2x] don't forget ln (a^b) = bln (a) [1/2xln (x)-1/2x] factorize by 1/2x and don't forget. Show more; indefinite-integral-calculator. George V. 915965594$. In order to use sin(lnx)dx in dv, we'll need to be able to integrate dv. Trouble integrating in an efficient way. { int frac{lnx}{x^2}:dx } there was a -sign problem in my result , Althouh you guys are doing great job thanks khan. Put u=lnx and v=1. This is also known as the antider. int ln(lnx) dx = xln(lnx) - int 1/lnx dx Using integration by parts with u = ln(lnx) and dv = dx, we get int ln(lnx) dx = xln(lnx) - int 1/lnx dx The antiderivative of 1/lnx is. − ln(tan x) cos x + ∫ 1 tan x 1 cos2 x ⋅cos xdx = − ln(tan x) cos x + ∫ csc xdx. Here is the proof I am reading: $$ egin{aligned} ln x y & = int_1^{x y} d t / t & =int_1^x d t / t+int_x^{x.